Log file not found

[skilled]

Hello All,

I have an issue with logfile.
I have already otrs6.0.16 on ubuntu18.4
When i am configuring: under Core->Log->LogModule->syslog, otrs will write the log to /var/log/syslog
But if I changed the setting from syslog to File, Core->Log->LogModule->Log:File and setting up the location of a log file to:
/tmp/otrs.log or /var/log/otrs.log
so I want that otrs write the logfile in separate file. I did not find where it saved.
I tried two places as I wrote above but there is no success.
When I restart the machine, the log file will be deleted, because I could read system log from otrs portal.

Any Tips may it help?

Thanks in advance